The present invention relates generally to a system and method for controlling the ignition characteristics of certain internal combustion engines, and particularly to a system and method for utilizing feedback from a combustion condition sensor in one cylinder and utilizing that feedback to adjust the air-fuel mixture to a more optimal ratio in other non-sensed cylinders.
Internal combustion engines are used in a wide variety of applications, including providing power for a variety of vehicles. Generally, such engines include one or more cylinders that each contain a piston designed for movement in a reciprocating manner. Each piston is connected to a crankshaft by a connecting rod that delivers force from the piston to the crankshaft in a manner that rotates the crankshaft. Power to drive the piston is provided by igniting an air-fuel mixture supplied to the cylinder on a side of the piston opposite the connecting rod. The air-fuel mixture is ignited by some type of ignition device, e.g. providing a spark across electrodes of a spark plug.
Air and fuel may be supplied to each cylinder by a variety of mechanisms, such as a fuel injection system. Regardless of how the air-fuel mixture is established, it is necessary to adjust or change the air-fuel mixture according to operating conditions. For example, application of greater throttle for increased engine speed requires a greater quantity of fuel. On the other hand, maintaining the engine operation at a lower rpm, requires a lesser quantity of fuel supplied to each cylinder. Generally, greater control over combustion conditions, e.g. air-fuel mixture, provides an engine designer with a greater ability to bring about a desired engine performance under a greater range of operating conditions.
Modern engines often utilize electronic fuel injection systems that inject specific amounts of fuel based on a stored fuel map. The fuel map effectively acts as a guide as to fuel injection quantities based on a variety of sensed parameters, such as engine speed, throttle position, exhaust pressure and engine temperature. However, none of these inputs are based on the actual combustion taking place in the one or more cylinders.
In some applications, oxygen sensors have been used to sense oxygen content of the combustion products, i.e. exhaust gasses. However, the sensed information has not been fully utilized in optimizing the air-fuel ratio in both sensed and non-sensed cylinders. It would be advantageous to have a methodology for correcting, for example, a fuel map controlling the fuel delivered to both sensed and non-sensed cylinders.
The present invention features a method for controlling the operation of an internal combustion engine having a plurality of cylinders and a controller that utilizes a fuel map. The method includes sensing a combustion condition in a sensed cylinder of an internal combustion engine. The method further includes determining whether the combustion condition is a desired combustion condition under the current operating parameters. The method also includes utilizing the difference between the combustion condition and the desired combustion condition to correct the fuel amounts introduced into a non-sensed cylinder.
According to another aspect of the present invention, a method is provided for controlling the operation of a watercraft. The method includes powering a watercraft with an internal combustion engine having a plurality of cylinders in which a cylinder of the plurality of cylinders is sensed for a specific combustion condition. The method also includes determining whether the combustion condition is desired under the current operating parameters and the comparing the actual combustion condition to a desired combustion condition. The fuel amount introduced into a non-sensed cylinder is then corrected based on the sensed combustion condition.
According to another aspect of the invention, a system is provided for controlling combustion in an internal combustion engine. The system includes a direct, fuel-injected, two-stroke engine having a plurality of cylinders with each cylinder being coupled to a fuel injector and a pair of electrodes for producing an ignition spark. The system further includes a combustion condition sensor coupled to a sensed cylinder of the plurality of cylinders. The sensor is able to produce an output indicative of the combustion condition. Also, the system includes a control unit having a pre-established fuel map for injecting specific quantities of fuel into each cylinder under a given operating condition. The control unit is able to adjust the fuel map for non-sensed cylinders based on the output of the combustion condition sensor.